s c a l e When Hardware Attacks Hardwear.io 27 September 2019 1 - PowerPoint PPT Presentation

s c a l e When Hardware Attacks Hardwear.io 27 September 2019 1

Attack exploitation space: time vs distance Remote key brute software protocol force relay attack side Fast Slow mitm channel Hardware attacks require: Hardware attacks • hardware vulnerabilities, or fault • hardware changes to target injection physical 2 Local

3 Attacker business case 𝑞 = 𝑜 ∗ 𝑤 − 𝑑 𝑤 − 𝑑 𝑔 p = profit v = value n = replications c v = variable costs c f = fixed costs 3

4 Let’s analyze some known attacks 1.EMV Man-in-the-Middle Hardware attack to bypass PIN verification of stolen payment cards 2.Retail hack Network penetration attack to retrieve cardholder credentials 3.Card sharing Relay attack to avoid paying TV subscription fees 4

5 EMV Man-in-the-Middle (1) Source: https://www.cl.cam.ac.uk/research/security/banking/nopin/ 5

6 EMV Man-in-the-Middle (2) 6

7 Retail hack 7

8 Card sharing (1) • Pay-TV decoders use smart cards to control video access • Subscription is in smart card 8

9 Card sharing (2) • Pay-TV decoders use smart cards to control video access • Subscription is in smart card • Distribution of session keys avoids need for individual subscriptions 9

10 Example attack business cases Attack Fixed Variable Value Replications Profit Cost Cost EMV MitM € 30K € 100 € 500 100 € 10 K Retail hack € 20K € 1 € 25 10K € 220 K Card sharing € 10K € 10 € 100 1M € 90 M Replications are key, but how is that bounded? • Application size (e.g. #potential victims) • Detection & mitigation • Replication effort To determine scalability, we need to quantify the replication effort 10

Attack phases and cost What parameters determine the attack cost? Identification Exploitation What it is finding a vulnerability replicate on target Frequency once repeated Speed How fast can we do this? Skill Required knowledge / experience Equipment Type of equipment Location Where is the attacker? Fixed cost Variable cost 11

Attack parameters What are typical attack parameters? Identification Exploitation Vulnerability Hardware Software Hardware Software Speed slow slow slow fast Skill expert expert proficient layman Equipment specialized standard specialized none Location local near local remote Scalable attack Scalable attacks need software exploitation! 12

13 How to find software vulnerabilities? Black-Box White-Box Model Based Source Code Fuzzing Binary Analysis Testing Review Attackers method Defenders method Effectiveness Most vulnerabilities are found white-box style! 13

14 Finding vulnerabilities in source code Software packages typically • vary between 10 and 10,000 KLoC • have 0.1 up to 10 vulnerabilities per KLoC  All products have software vulnerabilities Manual source code review performs at 100 LoC/hr  Finding a vulnerability in source code may take just one day 14

Binary analysis 15

Disassemble 16

Flow analysis 17

18 Software vulnerability hiding • Given the widespread presence of vulnerabilities there is an increasing desire to mitigate risk • Finding software vulnerabilities gets more difficult without access to source/binary code • Access to device software is increasingly restricted: • PC software used to be accessible (e.g. exe files) • Smart phone software is only visible for root • Set-Top-Box software is hidden, and encrypted in transit • How to attack a product protected with software encryption? internal 18

19 Attacking encrypted software Start Binary analysis exposes Exploitation yields logical vulnerability runtime control Encrypted software hides binary code Start Black-Box penetration testing Exploitation yields exposes logical vulnerability runtime control Black-Box penetration testing very inefficient Start Hardware attack breaks Binary analysis exposes Exploitation yields software confidentiality logical vulnerability runtime control Hardware attack offers two-step alternative: 1. Break software confidentiality 2. White-box binary analysis exposes logical vulnerability 19

Design flaw in Pay-TV SoC 20 Source: http://www.fredericb.info/2016/10/amlogic-s905-soc-bypassing-not-so.html

21 Secure boot chain broken by backdoor Attacker used hardware weakness to dump Boot Loader image Restricted 21

Boot Loader header analysis struct aml_img_header { // 64 bytes unsigned char magic[4];// "@AML" uint32_t total_len; Code Certificate Signature uint8_t header_len; uint8_t unk_x9; uint8_t unk_xA; Hash Verify Get key uint8_t unk_xB; uint32_t unk_xC; uint32_t sig_type; Hashed code Public key Verified Sig uint32_t sig_offset; uint32_t sig_size; uint32_t data_offset; Select uint32_t unk_x20; uint32_t cert_offset; Compare uint32_t cert_size; uint32_t data_len; uint32_t unk_x30; Stop Go uint32_t code_offset; uint32_t code_len; sig_type provides backdoor uint32_t unk_x3C; } aml_img_header_t; 22 that bypasses verification 22

23 Conclusions • Scalable attacks need software exploitation – Hardware attacks are laborious – Software vulnerabilities are ubiquitous – Software exploits are easy to replicate • Software encryption is inevitable for security – Binary analysis very successful in identifying vulnerabilities – Increasing number of products use encrypted software • Hardware attacks are scalable when – Software is encrypted – Shallow bugs (detectable black-box style) are absent – Used in the identification step to extract software – Deep software vulnerabilities are present 23

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